Adjustable sill and threshold assembly

ABSTRACT

An adjustable sill and threshold assembly in which the stationary sill includes a one-piece, molded base having a metal clad tread portion and a threshold portion having a groove extending longitudinally thereof. An adjustable threshold overlies the groove and has downwardly extending legs received in the groove with a pair of legs extending along an outer edge of the threshold cooperating with an upstanding leg formed by one edge of the metal cladding to form a labrynth seal against the entry of dirt and moisture into the groove. Moisture which may enter the groove along its opposite, inner edge or by condensation, can escape through drainage channels which extend from the groove to a collection chamber formed along the outer edge of the sill. The adjustable threshold is moved vertically by actuators which are slidably received in the groove and have inclined ramps cooperating with inclined ramps on inner surfaces of the legs of the threshold. The actuators are interlocked with portions of the groove and with the inclined ramps on the threshold to prevent separation of the threshold from the sill during adjustment, and a tool engaging portion of the actuators extends upwardly for engagement by a suitable tool to permit the actuators to be positioned longitudinally of the groove as required to provide the desired adjustment of the threshold.

United States Patent [191 Bursk et al.

[ ADJUSTABLE SILL AND THRESHOLD ASSEMBLY [75] Inventors: William Michael Bursk,

Middletown; David H. Pease, Jr., Cincinnati, both of Ohio [73] Assignee: Pease Company, Fairfield, Ohio [22] Filed: July 26, 1974 [21] Appl. No: 492,068

Primary Examiner-Philip C. Kannan Attorney, Agent, or Firm-Biebel, French & Bugg [57] ABSTRACT An adjustable sill and threshold assembly in which the [451 Aug. 26, 1975 stationary sill includes a one-piece, molded base having a metal clad tread portion and a threshold portion having a groove extending longitudinally thereof. An adjustable threshold overlies the groove and has downwardly extending legs received in the groove with a pair of legs extending along an outer edge of the threshold cooperating with an upstanding leg formed by one edge of the metal cladding to form a labrynth seal against the entry of dirt and moisture into the groove. Moisture which may enter the groove along its opposite, inner edge or by condensation, can escape through drainage channels which extend from the groove to a collection chamber formed along the outer edge of the sill. The adjustable threshold is moved vertically by actuators which are slidably received in the groove and have inclined ramps cooperating with inclined ramps on inner surfaces of the legs of the threshold. The actuators are interlocked with portions of the groove and with the inclined ramps on the threshold to prevent separation of the threshold from the sill during adjustment, and a tool engaging portion of the actuators extends upwardly for engagement by a suitable tool to permit the actuators to be positioned longitudinally of the groove as required to provide the desired adjustment of the threshold.

16 Claims, 15 Drawing Figures PATENTED AUG 2 6 I975 SHIT 1 UP 3 PATENTEDAUEZBIQYS 3. 900.967

saw 2 OF 3 FIG -5 4- 6 FIG -6 3 1 ADJUSTABLE SILL AND THRESHOLD ASSEMBLY BACKGROUND OF THE INVENTION Adjustable sill and threshold assemblies offer a distinct advantage over conventional, fixed constructions, in that they permit the formation of a weather tight seal between the assembly and weather stripping on the lower edge of a door associated therewith, despite variations in the door lower edge from a position parallel to the threshold and at the desired spacing. Considerable attention has been directed to the design of a suitable, adjustable assembly of this type, as exemplified by US. Pat. Nos. 3,273,287 and 3,762,100.

In US. Pat. No. 3,273,287 a U-shaped threshold is received in a channel formed in the sill and attached to the sill by means of screws passing through the threshold and sill. To obtain the desired spacing between the sill and threshold, washers are positioned on the screws to function as shims, with the number of washers being varied as required to obtain the desired spacing.

In US. Pat. No. 3,762,100 the sill is also provided with a channel receiving the adjustable threshold. A bolt is threaded into a portion of the sill within the channel and is provided with an enlarged head which bears on an under surface of the threshold to support it relative to the sill. The vertical adjustment of the threshold is accomplished by threading the supporting bolts inwardly or outwardly with respect to the sill. Sep arate retaining screws are then used to secure the threshold in place after adjustment thereof.

Each of the constructions described above relies upon bolts, screws or the like both to position the threshold with respect to the sill and also to fix the threshold in a desired position. In adjusting this type of assembly, the door must be opened, the screws or bolts adjusted, and the door closed to determine if the adjustment effected has been adequate to provide a weather tight seal between the door and the threshold. If not, the door must again be opened, further adjustment made, the door closed to check the seal, etc.

SUMMARY OF THE INVENTION The present invention provides an adjustable sill and threshold assembly in which the stationary sill includes a molded base of a suitable synthetic resinous material having a threshold receiving groove along an inner edge thereof and a tread portion having a series of drainage channels molded therein and extending downwardly and outwardly from the threshold receiving groove.

Preferably the tread portion of the base is provided with a cladding of aluminum or the like which extends from beneath the lower surface of the tread portion, around its outer edge, over the upper surface thereof, and terminates in a U-shaped section positioned within the groove.

The movable threshold, which is also constructed preferably of a synthetic resinous material, includes one downwardly extending leg lying along an innermost wall of the groove in the sill and a pair of spaced, parallel legs extending downwardly and cooperating with an upwardly projecting leg of the U-shaped portion of the metal cladding to form a labrynth seal therewith.

The groove is undercut along the innermost wall thereof at a number of spaced locations, and actuators are positioned in the groove at each of the undercut locations. The actuators which, similarly to the sill and threshold, are constructed of a synthetic resinous material, have inclined ramps which cooperate with inclined ramps on the legs of the threshold, so that upon sliding movement of the actuators longitudinally of the groove in which they are received, the threshold is adjusted vertically with respect to the sill.

The actuators are also provided with tool engaging portions which project upwardly adjacent the innermost surface of the groove and are engageable by the edge of a screw driver blade or the like to allow the actuators to be slid along the groove as required to obtain the desired vertical adjustment of the threshold.

The tool engaging portions of the actuators each have a shoulder which rides beneath the shoulder defined by the undercut section of the groove, and together with a flange of the actuator extending beneath the web of the U-shaped portion of the metal cladding, prevent separation of the actuator from the groove during adjustment of the threshold.

Each actuator also includes outwardly projecting ears which overlie upper surfaces of the inclined ramps of the threshold to prevent separation of the actuators and the threshold during and after adjustment operations. Thus, although the threshold is adjustable vertically with respect to the sill, it is prevented from being separated from the sill.

The inclination of the ramps on the threshold and actuators is selected to provide the amount of vertical travel of the threshold expected to be required for the amount of horizontal movement of the actuators available, and the specific synthetic resinous materials of which the components are constructed are selected for the most part in accordance with the structural characteristics required of each component.

To some extent, however, the requirement that the threshold remains in a selected vertical position after adjustment may affect the slope of the inclined ramps and the selection of materials which have coefficients of friction within some range of values. Additionally, the lower surfaces of the actuators and the bottom of the groove in the areas thereof which engage the lower surfaces of the actuators may be provided with small projections tc prevent inadvertent movement of the actuators when pressure is applied to the threshold or when the assembly is vibrated or subjected to shocks.

It will be seen, therefore, that the present invention provides an adjustable sill and threshold assembly in which the threshold may be adjusted vertically as desired, without resort to bolts, screws, shims or the like, but which is quickly and easily adjusted with respect to the lower edge of a door associated with the assembly while the door is closed to provide a weather tight seal between the threshold and weather stripping on the lower edge of the door.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a portion of a doorway incorporating the present invention;

FIG. 2 is a perspective view of the molded base of the assembly of the present invention;

FIG. 3 is an exploded perspective view of a threshold and metal cladding for the tread portion of the sill and threshold assembly;

FIG. 4 is a perspective view of an actuator used for adjusting the threshold with respect to the sill;

F IG. 5 is a plan view, partly in section, of a doorway incorporating the present invention;

FIG. 6 is a view taken on line 66 of FIG. 5;

FIG. 7 is a view, partly in cross section, showing a step in the assembly of the adjustable sill and threshold assembly of the present invention;

FIG. 8 is a plan view of a portion of the sill and threshold assembly;

FIG. 9 is a cross-sectional view taken generally along line 99 of FIG. 8;

FIG. 10 is a view similar to FIG. 9 but taken along line 10-10 of FIG. 8;

FIG. 1 1 is a perspective view showing the under surface of the adjustable threshold;

FIG. 12 is a perspective view of an actuator taken from the opposite side thereof shown in FIG. 4;

FIG. 13 is a cross-sectional view taken generally along line 1313 of FIG. 9;

FIG. 14 is a view similar to FIG. 13, but taken along line l414 of FIG. 10; and

FIG. 15 is a cross-sectional view through the sill and threshold construction of the present invention showing, in elevation, a lower portion of a door associated therewith.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A doorway incorporating the present invention, as seen in FIGS. 1, 5 and 15 of the drawings, includes the adjustable sill and threshold assembly 10 extending between opposed jambs 12 and 14 and beneath a door 16 mounted on the jamb 14 by means of hinges 18. The jambs l2 and 14 may carry suitable weather stripping 20, engageable with the front face of the door, and trim members 22 attached to the jambs by means of clips 24 which also include legs 26 through which the jambs may be nailed to studs 28 framing the doorway.

As best seen in FIGS. through 4, 6 and 15 of the drawings, the assembly 10 includes a base member 30, a movable threshold 32, metal cladding 34 and a series of actuators 36. The molded base member 30 constitutes a fixed sill having a threshold receiving groove 38 extending along an inner edge thereof and a tread portion 40 projecting downwardly and outwardly from the groove 38. The base member 30 may also include grooves 42 adjacent each end thereof for receiving the lower ends of the jambs and trim members associated therewith. Alternatively this feature can be eliminated and the sill and threshold merely positioned between the jambs and associated trim members.

The groove 38, as shown in FIG. 2, is provided with a plurality of undercut sections 44 in an inner wall 46 thereof and at each section 44 the bottom of the groove is provided with a plurality of pyramid shaped projections 47. The undercut portions 44 define shoulders 48, as seen in FIG. 7, terminating in slots 50. A series of drainage channels 52 are formed in the tread portion 40 and extend outwardly from the outer wall 58 of the groove 38 to the outer edge 56 of the tread portion of the base member 30.

The metal cladding 34, which is preferably formed of aluminum or the like, includes a portion 59 extending from beneath the tread portion 40, around the outer edge 56 thereof, over the upper surface of the tread portion and thence downwardly into the groove 38, terminating in a U-shaped section 60 having a web portion 62 and an upwardly projecting leg 64.

It will be noted particularly from FIG. 6 of the drawings, that the cladding is spaced from the outer edge of the tread portion and forms a collection chamber 66 extending the length of the sill and communicating with the drainage channels 52 at their outer ends. The ends of the chamber 66 are open for full drainage at 67 (FIG. 5). The U-shaped portion 60 may also include a short flange 68 which underlies a shoulder 70 formed along the outer wall of the groove 38 to lock the cladding in position along this portion thereof.

The movable threshold 32 includes a cap portion 72, a downwardly extending leg 74 adapted to lie adjacent the inner wall 46 of the groove 38, and a pair of parallel legs 76 and 78 which project downwardly from the cap portion 72 adjacent the outer wall 58 of the groove 38 and straddle the upwardly projecting leg 64 of the U- shaped portion 60 of the metal cladding 34. With this construction, as best seen in FIG. 6 of the drawings, when the threshold 32 is in place, the legs 78, 64 and 76 cooperate to form a labrynth seal against the entry of moisture into the groove 38 adjacent the outer wall 58 thereof.

As best seen in FIG. 11 of the drawings, the legs 76 and 74 of the threshold 32 are provided with a series of pairs of inclined ramps 80 and 82 on their opposed inner surfaces. The pairs of opposed ramps 80 and 82 are provided on the legs 76 and 74 at a plurality of locations corresponding in spacing and number to the relieved sections 44 formed in the inner wall of the groove 38, satisfactory results having been obtained with five such paired ramps in a doorway of standard width.

The actuators 36, as best seen in FIGS. 4 and 12, each include a pair of spaced legs 84 and 86 terminating in outwardly turned flanges 88 and 90. An extension 92 of the flange carries an upwardly projecting tool engaging portion 94, which may be notched along opposite edges thereof as indicated at 96. It will also be noted from FIG. 12 of the drawings that the lower surfaces of the actuators are provided with pyramid shaped projections 97, similar to projections 47 in the groove 38. The projections 47 and 97 thus prevent inadvertent sliding movement of the actuators once they have been positioned.

Each of the legs 84 and 86 is provided with an inclined ramp portion 98 and 100 which slopes downwardly from adjacent one end of the actuator beneath outwardly projecting ears 102 and 104, and each of the ears has a lower surface extending substantially parallel to the upper surfaces of the inclined ramps 98 and 100. The ramps 98 and 100 and the lower surfaces of the ears 102 and 104 are complementary to the upper and lower surfaces 106 and 108 of the inclined ramps 80 and 82 of the threshold 32, as best seen in FIG. 7 of the drawings.

With this construction, it will be apparent that the actuators can be assembled with the threshold 32 by inserting the lower ends of the ramps 80 and 82 between the ramps 98 and 100 and the overlying under surfaces of the ears 102 and 104. With each of the actuators positioned adjacent the lowermost ends of their respective pairs of ramps 80 and 82, the sub-assembly of the threshold 32 and actuators 36 can be lifted into position over the threshold groove 38 with the tool engaging portions 94 of the actuators 36 aligned with the notches 50 along the inner wall 58 of the groove 38.

This will be apparent from FIGS. 7 and 8, wherein a portion of the threshold 32 and an attached actuator 36 is shown with the portion 94 of the actuator aligned with a notch 50. Thereafter, the sub-assembly of actuators and threshold is. moved downwardly in the direction indicated by the arrows in FIG. 7 of the drawings until the lower surfaces of the flanges 88 and 90 rest on the bottom of the groove 38.

The inner wall of the groove 38 in the region of the recesses 44 and the notches 50 slopes inwardly, toward the bottom of the groove as indicated at 106 in FIGS. 9 and 10 of the drawings. Therefore, as the actuators move towards the bottom of the groove 38, the feet 88 slip beneath the web 62 of the U-shaped portion 60 as best seen in FIG. 6 of the drawings. At this time, the assembly is in the configuration shown in FIGS. 9 and 13 of the drawings.

Any suitable tool, such as the blade 108 of a screw driver, may then be inserted beneath the cap portion 72 of the threshold from a position laterally of the assembly, engaging the right hand notch 96 as seen in FIG. 13 of the drawings to move the actuators to the left as indicated by the arrow in FIG. 13. As each of the actuators is moved in this manner, the complementary inclined ramps on the actuators and threshold cause the threshold to move downwardly as indicated by the vertical arrow in FIG. 14 of the drawings.

This not only decreases the height of the threshold 32 but causes the shoulder 110 on the tool engaging portion 94 to slide beneath the shoulder 48 formed by the undercut section in the wall 46 of the groove 38. Each of the actuators is, therefore, restrained against movement in a vertical direction by the engagement of the foot 88 thereof with the under surface of the web 62 and the shoulder 110 with the under surface of the shoulder 48.

The threshold 32 is, of course, prevented from separating from the actuators 36 by the outwardly projecting ears 102 and 104 on the actuators which engage the upper surfaces 106 of the inclined ramps 80 and 82. As a result, the threshold cannot separate inadvertently from the sill during or after adjustment of the assembly.

As indicated in FIG. 15 of the drawings, the usual door construction will include weather stripping of some type on the lower edge of the door which, when the threshold is adjusted properly, will form therewith a weather tight seal. To obtain the proper adjustment of the threshold 32 with respect to the lower edge of the door 16, the door may be closed and a suitable tool inserted beneath the rear lip 112 of the weather strip to engage the portion 94 of each actuator and slide it along the groove 38 until the proper vertical position of the threshold with respect to the lower edge of the door is established.

The combination of the legs 76 and 74 and the upstanding leg 64 forms a seal against the entry of moisture from the outer side of the sill into the groove 38. Should moisture enter the groove 38 from adjacent the inner side of the sill, or from condensation, it may drain therefrom through the drainage channels 52 into the collection chamber 66 from whence it may drain freely out of the assembly from both open ends 67 of chamber 66.

From the above it will be apparent that the present invention provides an adjustable sill and threshold assembly of rugged construction which can be quickly and easily adjusted to provide the desired fit of the upper surface of the threshold with the lower edge of a door associated with the assembly.

' While the form of apparatus herein described constitutesa preferred embodiment of the invention, it is to beunderstood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention. r

What is claimed is: 1

1. An adjustable sill and threshold assembly comprisa. a stationary sill, I

b. means defining a'threshold groove extending longitudinally of said sill,

c. a movable threshold mounted on said sill over said groove, and

d. actuating means received in said groove beneath said threshold for adjusting said threshold vertically with respect to said stationary sill upon movement of said actuating means longitudinally of said groove.

2. The assembly of claim 1 wherein:

a. said sill comprises a molded base.

3. The assembly of claim 2 wherein said molded base includes:

a. a first portion containing said groove, and

b. a tread portion sloping downwardly and outwardly fromsaid groove containing portion.

4. The assembly of claim 3 further comprising:

a. means defining drainage channels in said tread portion extending outwardly from and in communication with said threshold groove 5. The assembly of claim 3 further comprising:

a. means for cladding said tread portion of said molded base,

b. said cladding means defining with a distal portion of said tread portion of said base a collection chamber in communication with said drainage channels adjacent outer ends thereof. I

6. The assembly of claim 1 further comprising:

a. leg means on said threshold extending downwardly therefrom, and

b. leg means extending upwardly from said threshold groove and forming with said threshold leg means a labrynth seal.

7. The assembly of claim 1 wherein:

a. said actuating means and said threshold have inclined ramp means in engagement with each other for causing the vertical adjustment of said threshold upon said movement of said actuating means longitudinally of said groove.

8. The assembly of claim 7 wherein:

a. said ramp means are interconnected to prevent separation of said actuating means and said threshold during adjustment thereof.

9. The assembly of claim 8 further comprising:

a. means for preventing vertical movement of said actuating means during adjustment of said threshold.

10. The assembly of claim 1 further comprising:

a. tool engaging means connected to said actuating means and accessible from positions disposed laterally of said threshold.

11. The assembly of claim 1 further comprising:

a. means for preventing separation of said threshold from said sill dun'ng vertical adjustment of said threshold.

12. The assembly of claim 5 further comprising:

a. a portion of said cladding positioned in said groove and providing upwardly projecting leg means, and

b. leg means on said threshold extending downwardly into engagement with said-upwardly projecting leg means on said cladding and forming therewith a labrynth seal.

13. The assembly of claim 1 further comprising:

a. means projecting downwardly from a lower surface of said actuating means for engagement with a bottom of said groove to resist said movement of said actuating means longitudinally of said groove.

14. The assembly of claim 1 further comprising:

a. means projecting upwardly from a bottom of said groove for engagement with a lower surface of said actuating means to resist said movement of said actuating means longitudinally of said groove.

15. The assembly of claim 14 further comprising:

a. means projecting downwardly from a lower surface of said actuating means and cooperating with said upwardly projecting means on said bottom of said groove to resist said movement of said actuating means longitudinally of said groove.

16. An adjustable sill and threshold assembly comprising:

a. a stationary sill including a molded base having a downwardly and outwardly sloped tread portion and a threshold groove having inner and outer walls extending longitudinally of said base adjacent an inner edge thereof,

b. means defining a plurality of discrete, undercut sections in said inner wall of said threshold groove,

c. means defining a plurality of drainage channels in said tread portion of said base extending downwardly and outwardly from said outer wall of said threshold groove to an outer edge of said tread portion,

d. metal cladding covering an upper surface of said threshold portion of said base and extending around said outer edge of said tread portion in spaced relationship thereto and defining therewith a collection channel communicating with lower ends of said drainage channels,

. e. an inner edge of said cladding terminating in a substantially U-shaped section positioned in said threshold groove and including a leg projecting upwardly from said groove,

f. a threshold having a cap portion overlying said threshold groove, an inner leg extending downwardly from said cap portion in contiguous relationship to said inner wall of said groove, and a pair of legs extending downwardly from said cap portion adjacent-said outer wall of said groove and straddling said upwardly projecting leg of said U- shaped portion of said cladding to define therewith a labrynth seal,

g. a plurality of actuators received in said groove at said undercut sections thereof for limited sliding movement longitudinally of said groove in the vicinity of said undercut sections,

h. outwardly projecting flange means on said actuators underlying said U-shaped portion of said metal cladding to restrain said actuators against vertical movement within said groove,

i. tool engaging portions formed on said actuators projecting upwardly therefrom adjacent said inner wall of said groove and accessible by a tool inserted beneath said cap adjacent said inner wall of said groove,

j. said tool engaging portion having a shoulder portion thereon cooperating with a shoulder defined by said undercut section of said groove to restrain vertical movement of said actuator within said groove,

k. inclined ramp means projecting inwardly from legs of said threshold in opposition to each other,

1. complementary inclined ramp means on said actuators in slidable engagement with lower surfaces of said inclined ramps on legs of said threshold, and

m. outwardly projecting ears on said actuators extending outwardly over said upper surfaces of said ramps on said threshold and preventing separation of said actuators from said threshold. 

1. An adjustable sill and threshold assembly comprising: a. a stationary sill, b. means defining a threshold groove extending longitudinally of said sill, c. a movable threshold mounted on said sill over said groove, and d. actuating means received in said groove beneath said threshold for adjusting said threshold vertically with respect to said stationary sill upon movement of said actuating means longitudinally of said groove.
 2. The assembly of claim 1 wherein: a. said sill comprises a molded base.
 3. The assembly of claim 2 wherein said molded base includes: a. a first portion containing said groove, and b. a tread portion sloping downwardly and outwardly from said groove containing portion.
 4. The assembly of claim 3 further comprising: a. means defining drainage channels in said tread portion extending outwardly from and in communication with said threshold groove.
 5. The assembly of claim 3 further Comprising: a. means for cladding said tread portion of said molded base, b. said cladding means defining with a distal portion of said tread portion of said base a collection chamber in communication with said drainage channels adjacent outer ends thereof.
 6. The assembly of claim 1 further comprising: a. leg means on said threshold extending downwardly therefrom, and b. leg means extending upwardly from said threshold groove and forming with said threshold leg means a labrynth seal.
 7. The assembly of claim 1 wherein: a. said actuating means and said threshold have inclined ramp means in engagement with each other for causing the vertical adjustment of said threshold upon said movement of said actuating means longitudinally of said groove.
 8. The assembly of claim 7 wherein: a. said ramp means are interconnected to prevent separation of said actuating means and said threshold during adjustment thereof.
 9. The assembly of claim 8 further comprising: a. means for preventing vertical movement of said actuating means during adjustment of said threshold.
 10. The assembly of claim 1 further comprising: a. tool engaging means connected to said actuating means and accessible from positions disposed laterally of said threshold.
 11. The assembly of claim 1 further comprising: a. means for preventing separation of said threshold from said sill during vertical adjustment of said threshold.
 12. The assembly of claim 5 further comprising: a. a portion of said cladding positioned in said groove and providing upwardly projecting leg means, and b. leg means on said threshold extending downwardly into engagement with said upwardly projecting leg means on said cladding and forming therewith a labrynth seal.
 13. The assembly of claim 1 further comprising: a. means projecting downwardly from a lower surface of said actuating means for engagement with a bottom of said groove to resist said movement of said actuating means longitudinally of said groove.
 14. The assembly of claim 1 further comprising: a. means projecting upwardly from a bottom of said groove for engagement with a lower surface of said actuating means to resist said movement of said actuating means longitudinally of said groove.
 15. The assembly of claim 14 further comprising: a. means projecting downwardly from a lower surface of said actuating means and cooperating with said upwardly projecting means on said bottom of said groove to resist said movement of said actuating means longitudinally of said groove.
 16. An adjustable sill and threshold assembly comprising: a. a stationary sill including a molded base having a downwardly and outwardly sloped tread portion and a threshold groove having inner and outer walls extending longitudinally of said base adjacent an inner edge thereof, b. means defining a plurality of discrete, undercut sections in said inner wall of said threshold groove, c. means defining a plurality of drainage channels in said tread portion of said base extending downwardly and outwardly from said outer wall of said threshold groove to an outer edge of said tread portion, d. metal cladding covering an upper surface of said threshold portion of said base and extending around said outer edge of said tread portion in spaced relationship thereto and defining therewith a collection channel communicating with lower ends of said drainage channels, e. an inner edge of said cladding terminating in a substantially U-shaped section positioned in said threshold groove and including a leg projecting upwardly from said groove, f. a threshold having a cap portion overlying said threshold groove, an inner leg extending downwardly from said cap portion in contiguous relationship to said inner wall of said groove, and a pair of legs extending downwardly from said cap portion adjacent said outer wall of said groove and straddling said upwardly projecting leg of said U-shaped portion of said claddIng to define therewith a labrynth seal, g. a plurality of actuators received in said groove at said undercut sections thereof for limited sliding movement longitudinally of said groove in the vicinity of said undercut sections, h. outwardly projecting flange means on said actuators underlying said U-shaped portion of said metal cladding to restrain said actuators against vertical movement within said groove, i. tool engaging portions formed on said actuators projecting upwardly therefrom adjacent said inner wall of said groove and accessible by a tool inserted beneath said cap adjacent said inner wall of said groove, j. said tool engaging portion having a shoulder portion thereon cooperating with a shoulder defined by said undercut section of said groove to restrain vertical movement of said actuator within said groove, k. inclined ramp means projecting inwardly from legs of said threshold in opposition to each other, l. complementary inclined ramp means on said actuators in slidable engagement with lower surfaces of said inclined ramps on legs of said threshold, and m. outwardly projecting ears on said actuators extending outwardly over said upper surfaces of said ramps on said threshold and preventing separation of said actuators from said threshold. 